Machine Safety Resource Center

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Controls engineers need a variety of information on machine-safety topics.

Machine safety has become an even more important machine design concern as it must provide responsible protection for operators and technicians in a manner that keeps the machines running to the fullest degree possible with intelligent use of light curtains, interlock switches, safety relays, safety modules, programmable safety controllers, and other essential machine safety devices to monitor, prevent, and react to machine upsets.

Timely news, back-to-basics primers, feature articles, technical white papers and descriptions of the latest products all provide valuable insights that can be used in designing and building machine controls.

What Does NFPA 70E Allow?
FPA 70E Is Tough to Work Through. What Can Somebody Tell Us About This?

Case-and-Tray-Packer Builder Meets the Needs of Varied Industries
Once Upon a Packer Builder: Field Service Engineers and Operator Interface Keep Customers Happy Ever After

Focus On: Retaining Automation Know-How
ControlDesign.com
This insightful look at our February 2010 cover story, "Stick to the Playbook" (www.ControlDesign.com/reuseknowhow) examines how machine builders are creating standards and reusable modular design to retain the work and the knowledge of their engineers. Control Design's editorial staff interviews Pat Phillips, engineering manager at Haumiller, which builds high-speed, automated assembly machines, and Chris Lovendahl, sales manager at Concep Machine, makers of special-purpose machine and factory-automation systems, to get a closer look at how those two companies are retaining their automation know-how.

FISCO ic and FNICO Are Interchangeable...for Now
FISCO, FNICO Are Like Two Clouds of Flammable Gases Passing in the Night

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White Papers: In Depth Research

Redundancy in Technological Systems
Author: Helge Hornis, Ph D, Manager, Intelligent Systems, Pepperl+Fuchs
Posted: 03/10/2010
Redundancy is a concept frequently applied in technological systems. When investigating in detail why redundancy is used, one will find that there are many reasons for doing this. Looking at several redundant implementations should make this clear. Still, all aspects of redundancy have one idea in common: increased ability to control a system even when problems occur.

Functional safety systems are probably the most common automation solutions based on redundancy. Here the rationale is to provide a control system that is able to safely shut down a machine in case of emergency. Depending on a detailed safety evaluation, safety solutions of varying complexity can be used to address the particular needs of the application. Safety systems are still designed to comply with EN954, which divides applications into five classes between B at the low end and CAT 4 at the upper end. To show that not all redundant systems are equal, let's focus on two scenarios. Figure 1 shows a safety system where a number of redundant-safe input devices (e-stops and magnetic interlock switches) are connected redundantly in a series. These safety strings are then connected to a safety relay, which is ultimately responsible to shut down motors, drives or other potentially harmful devices. Consider a situation where one of the safe contacts on a magnetic safety switch is welded or simply sticky. Due to the redundant nature of the safety string, the machine will still come to a safe shutdown as soon as the door, evaluated by this magnet, is opened. Even better, the safety relay will not even allow a restart of the system after the door has been closed. The reason for this is that the safety relay demands that as soon as one of its safe inputs shows an open contact, the second input must also go open, clearly a condition not satisfied due to the welded contact. Unfortunately, it is rather trivial to trick the safety relay. All one has to do is open and close another door. As soon as this happens, the safety relay detects its two inputs as open, making this a resettable condition. As soon as this happens, the redundant nature of the system is compromised. All it takes is a second fault at the magnetic door switch, and it will not be able to result in safe system shutdown.

Pneumatic Safety Systems and Cylinder Speed Control
Author: Eric Cummings and Steve Boyette, ROSS Controls
Posted: 11/06/2009
The advancements in automation systems have led to tremendous increases in productivity for manufacturers. Machine controls utilizing sensing and verifi cation of the product and position sensing of machine components allows for higher speeds of equipment and improvements in quality. Improvements in safety have also been achieved, greatly reducing the instances where operators are required to interact with the equipment during operation. However, automated machines are not autonomous. Material deviations or component malfunctions still require an operator to investigate and alleviate the situation. Because of this, operators and maintenance personnel must access potentially hazardous areas in the machine for functions such as clearing jams and other routine production related issues. These production related issues must of course be done in a safe manner; advancements in safety control systems are helping to make this possible.

Valves Enhance Machine and Worker Safety
Author: Eric Cummings and Steve Boyette, ROSS Controls
Posted: 10/20/2009
It is easy to say that "Safety is everyone's goal," but what is really meant by that? Sound workplace safety practices can reduce the risk of injury to not only machine operators but to other people such as maintenance technicians. Sound workplace safety practices can also reduce the risk of accidental damage to machinery and other company assets, or harm to the environment. Common industry standards acknowledge that there is no such thing as zero risk, but nonetheless provide guidance to machine builders and operators regarding how to minimize risks. This is commonly referred to as machine safeguarding. Here's a look at some key factors.

Video Analytics and Security
Author: Schneider Electric
Posted: 08/21/2009
Using video data to improve both safety and ROI.

Most companies are gathering trillions of bytes of data, day after day, at no small cost, and then doing very little with it. Worse still, the data often is not serving its primary function very cost-effectively.

The "culprit," so to speak, is video surveillance data, the information captured by the video cameras that are used throughout most modern facilities.

But the situation is changing rapidly, thanks to an application called Video Analytics. This white paper looks at the new software technology, and how it can be used to leverage video data for better security and business performance.

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